I can think of ways to measure capacity or performance of a service desk, but not productivity. What does it produce that is measurable?_________________"Method goes far to prevent trouble in business: for it makes the task easy, hinders confusion, saves abundance of time, and instructs those that have business depending, both what to do and what to hope."
William Penn 1644-1718

I call that performance, and you need either to deal in averages with relatively large numbers, or to have very clear definitions of incident categories so that you compare like with like.

It is relatively easy to collect data recording incident duration, but understanding what that data tells you is a bit more difficult.

Some (by no means exhaustive) factors that are relevant:

- how quickly it is possible to interpret what the caller is telling you (and not all callers are alike)

- how quickly you can diagnose the symptoms and identify the action required to restore service; this depends on:
- how well your skill sets and experience match this particular issue
- the complexity of the system that had the incident

- how quickly any approvals or authorization take (e.g. to make a change)

- how long the restorative action takes (e.g. a reboot can have a service back in five minutes or three hours depending on recovery requirements and on launch time for applications; also, a reboot may have to be deferred until other users of the server are no longer a higher priority)

- whether higher priority tasks cause this one to be held pending free resources

Isolating how fast individuals are working on the incidents from all that is not always simple.

So, it's much easier to deal with averages. But then you have no statistical data to determine whether a particular incident took longer to resolve than it ought. Also, you have to have a way of ensuring that an apparent trend over time is not caused by some factor affecting the nature of incidents rather than the nature of the resolution process._________________"Method goes far to prevent trouble in business: for it makes the task easy, hinders confusion, saves abundance of time, and instructs those that have business depending, both what to do and what to hope."
William Penn 1644-1718

In addition to the valuable things that others wrote. I would like to add the following for you to understand the idea of KPI's and measurements.

So in your scenario, you would like to measure the performance or "how fast an incident can be resolved".

First of all you need to ensure that you are collecting the correct data, then make sure that the measurements you are about to initiate are affective, when dealing with KPI's ask your self is the KPI a good reflect of the improvement I am about to implement?

For Example what improvement can you make to improve the performance or how fast an incidents can be resolved as you mentioned?

Introduce technical training to your staff(This is an improvement). % reduction of resolution time due to staff training (This is the KPI)

Implement or introduce a knowledge base system(Improvement). % reduction of resolution time due to the introduction of Knowledge database(KPI) and so on.

Subsequently you can get the results and show the benefits to the management._________________Ali Makahleh
Configuration Management(Blue Badge),
ITILV2 Service Manager(Red Badge),
ITILV3 Expert(Lilac Badge) Certified.

“If you can't describe what you are doing as a process, you don't know what you're doing." W. Edwards Deming.